One example of a bench top miter saw power tool 10 is shown in FIG. 1. The miter saw includes a saw assembly 12 supported on a platform assembly 14. The platform assembly defines a work surface 16 for supporting a workpiece, and a guide fence assembly 18 for supporting the workpiece during a cutting operation. The platform assembly also includes an adjustment mechanism for adjusting the height, miter angle and/or bevel angle of the saw assembly 12. The saw assembly 12 further includes a saw blade 20 that is supported by an arm assembly 24. The arm is also configured as an upper guard to cover the top portion of the cutting zone formed by the rotating blade 20. The arm assembly 24 supports the drive motor assembly M and a handle mechanism 26 and is mounted to the platform assembly 14 at an arm pivot mount 28 between the arm assembly 24 and a support structure of the platform assembly. The pivot mount may be configured to bias the saw assembly to a raised orientation, as shown in FIG. 5, which allows access to the work surface 16 to position a workpiece W for a miter cut. The arm pivot mount 28 allows the operator to manually pivot the saw assembly downward, by way of the handle 26, to perform the cut, as illustrated in FIG. 6.
The saw assembly 12 includes a lower guard 22 that is pivotably mounted to the arm assembly 24 to cover the rear portion of the cutting zone, as shown in FIG. 1. The lower guard 22 envelops the arm assembly/upper guard 24 and pivots from a position fully encasing the saw blade, as shown in FIG. 2, to a position in which the lower guard substantially overlaps the arm assembly/upper guard 24, as shown in FIG. 1. The lower guard 22 may include a bushing 23 (FIG. 6) at its lower edge to contact the workpiece W when the saw assembly 12 is pivoted during a miter cut. A dust collection system 17 may be included in the power tool to collect dust and debris during a cut. As shown in FIGS. 5-6, the power tool may also include a slide assembly 29 having a yoke 52 that integrates with the arm 28 for the saw assembly. The yoke is horizontally movable relative to the platform so that the saw can be moved linearly across the workpiece.
Certain safety regulations require that the rear portion of the cutting zone (i.e., the portion adjacent the arm pivot mount 28 of the saw assembly 12) be covered by a non-removable guard. In prior power saws the rear edge 25 (FIG. 1) of the arm assembly/upper guard 24 extends below the midline of the saw blade in order to provide the desired blade protection. However, during procedures in which a tall workpiece is butted up to the fence 18, such as shown in FIG. 5, the bottom edge 25 of the upper guard can contact and interfere with the workpiece.
Consequently there is a need for a safety device for the rear portion of the cutting zone that meets the requirements for a non-removable guard but that does not interfere with the use of the power tool.